Past Event: Oden Institute Seminar

A numerical strategy for unsteady simulation of low Mach number reacting flows subject to electric fields

Lucas Esclapez, Lawrence Berkeley National Laboratory (LBNL)

Abstract

Experiments have demonstrated that electric fields can be employed in combustion applications to control the flame stabilization and reduce pollutant emissions. However, the multi-scale nature of the physical processes has so far preventedthe development of efficient unsteady numerical methods, able to further analyze the interactions between turbulent flows,combustion kinetics and electric fields. We propose an algorithm for low Mach number combustion that incorporates the chemical production of charged species and their transport induced by electric field. The strategy relies on the multi-implicit spectral deferred correction (MISDC) approach that allows for a strong and efficient coupling of the stiff drift/diffusion and reaction terms with the slower advection terms. Along with the momentum, energy and species transport equations, a Poisson equation is solved to provide a consistent electrostatic potential. To overcome the stringent time-stepping constraint due to the fast electron motion, a non-linear implicit solve of the electrostatic potential and electron number density equations is used. For the strategy to be amendable to large scale computations, the non-linear system is solved using a Jacobian-Free Newton Krylov method, for which a preconditioner is developed. We will present the details of the method and demonstrate its capabilities on steady and unsteady of one-dimensional cases. This is joint work with J. B. Bell and M. S. Day. Bio: Dr. Lucas Esclapez is a post-doctoral researcher in the Center for Computational Sciences and Engineering, at Lawrence Berkeley National Laboratory (LBNL). His current research focuses on the development of high-performance simulation tools to study the interactions between flames and electric fields. Prior to his appointment at LBNL, he was a post-doctoral researcher at the Center for Turbulence Research (Stanford, USA. 2015-2016) and CERFACS (Toulouse, France. 2016-2018) working with Large Eddy Simulations (LES) to investigate the combustion process in industrial systems. Dr. Esclapez received is PhD from CERFACS in 2015 where he was studying aeronautical gas turbines ignition.